Cardiovascular disease 1

Question 1

Define ischaemic heart disease

Answer 1

• Inadequate blood supply to the myocardium due to
  1) reduced coronary blood flow-atheroma/thrombus
  2) myocardial hypertrophy usually due to systemic hypertension

Question 2

What is the pathogenesis of IHD?

Answer 2

• Acute & chronic ischaemia
• Autorgulation of coronary blood flow breaks down in occlusion
• Low diastolic flow esp in subendocardial tissue
• Active aerobic metabolism of cardiac muscle
• Myocyte dysfunction/death due to ischaemia

Question 3

Name some IHD syndromes and risk factors

Answer 3

• Angina Pectoris: stable, unstable, variant
• Acute coronary syndrome: acute MI, unstable angina
• Sudden cardiac death
• Chronic IHD
• Smoking, obesity, high cholesterol, hypertension,diabetes

Question 4

Describe acute ischaemia

Answer 4

• Atheroma & acute thrombosis/haemorrhage
• Lipid rich plaques most unstable
• Regional transmural MI
• Treatment-thrombolysis
• Causes myocardial stunning
• Diagnosis-clinical, blood cardia proteins

Question 5

Describe an MI morphology

Answer 5

• 1 week= pale, thin, granulaton tissue & fibrosis

- After 4 weeks dense fibrous scar cannot tell how old MI is

Question 6

Describe a subendocardial MI, how is this different to transmural MI?

Answer 6

• Subendocardial myocardium poorly perfused
• Subendocardial myocardium can infarct without any acute coronary occlusion
• SMI= area of ischemic necrosis is limited to the endocardium
• TMI= Ischaemic necrosis of full thickness of myocardium

Question 7

What blood markers are used to check cardiac myocyte damage?

Answer 7

• Troponin I & T= detectable upto 7days after, raised post MI & pulmonary embolism, HF, myocarditis
• Creatine Kinase= detectable upto 3 days after

Question 8

What are complications of an MI?

Answer 8

• Arrhythmia=VF& sudden death
• Ischaemic pain
• Left V failure & shock
• Pericarditis
• Cardiac mural thrombus & emboli
• DVT &PE
• Myocardial rupture-tamponade, V septal perforation, papillary muscle rupture
• Ventricular aneurysm
• Autoimmune pericarditis

Question 9

Describe chronic IHD

Answer 9

• Coronary artery atheroma produces myocardial ischaemia & angina on exertion
• Risk of sudden death/MI
• Unstable angina evolving
• Variant angina- coronary arterial spasm

Question 10

What is familial hypercholestrolaemia?

Answer 10

• Mutation in genes involved in cholesterol metabolism: Apolipoprotein B, Low density lipoprotein receptor gene
• Autosomal dominant
• Heterozygous-develop xanthomas, corneal Marcus, early atherosclerosis treat with statins

Question 11

What are causes of primary hypertension?

Answer 11

• Physiological systems interacting over long periods of time
• Cardiac baroreceptors
• Renin-angiotensin-aldosterone system
• Kinin-kallikrekin system
• Naturetic peptides
• Autonomic NS
• Adrenergic receptor system
• Autocrine factors produced by blood vessels

Question 12

How can sodium cause hypertension?

Answer 12

• All inherited forms share inc net salt balance as common pathway
• Inc intravascular vol & vol delivery to heart augment CO & BP
• Resulting tissue perfusion exceeds metabolic demand leading to auto regulation of blood flow to inc vasoC to reduce blood flow
• Results in steady state hemodynamic pattern of elevated BP w/inc systemic vascular resistance & normal CO

Question 13

Name the main causes of secondary hypertension

Answer 13

• Renal: renal stenosis
• Endocrine: hyperthyroidism
• Cardiovascular
• Neurologic
• Phaeochromocytoma

Question 14

Describe the Renin-Angiotensin-Aldosterone pathway

Answer 14

• Renin= synthesised, stored &released from juxtaglomerular apparatus in wall of afferent arterioles of kidney. Cleaves angiotensinogen to angiotensin I
• Angiotensin I–>angiotensin II (active)
• Angiotensin II=potent vasoC, short 1/2 life, stimulates adrenal cortex to produce aldosterone
• Aldosterone= mineralocorticoid, renal action causes Na & H2O retention, circulating blood vol inc

Question 15

What is renal artery stenosis and how can this lead to hypertension?

Answer 15

• Reduced BP in kidney- afferent arterioles
• Juxtaglomerular apparatus stimulated to produce renin
• Renin-angiotensin system stimulates adrenal cortex zona glomerulosa cells to produce aldosterone= inc BP

Question 16

What is coarctation of the aorta?

Answer 16

• Congenital narrowing distal to origin of L subclavian
• Hypotension in kidneys leads to renin release
• Asymptomatic
• Detected by difference in bp between arms & legs
• Surgical correction

Question 17

What is Conn’s Syndrome?

Answer 17

• Caused by excess aldosterone secretion (by adrenocortical adenoma, micro nodular hyperplasia, NaH2O retention, elevated aldosterone, low renin, potassium loss)
• Diagnosed by CT scans of adrenal
• Muscular weakness, arrhythmias, parasthaesia, metabolic alkalosis

Question 18

What is a Phaeochromocytoma?

Answer 18

• Tumour of adrenal medulla
• Presents due to secretion of vasoC catecholamines-adrenaline & noradrenaline
• Also present: pallor, headaches, sweating, hypertension, nervousness
• Diagnosed by 24hr urine collection for adrenaline metabolites

Question 19

What is Cushing’s Disease?

Answer 19

• Overproduction of cortisol by adrenal cortex
• Cortisol=Metabolic effects-sympathetic NS, mineralocorticoid effect on kidneys=hypertension
• Caused by adenoma/ adrenocortical neoplasm, pituitary adenoma (Cushing’s Syndrome)

Question 20

What are the effects of hypertension? Describe

Answer 20

• Cardiovascular: hypertensive HD (inc LV BP–> LV hypertrophy without dilatation, sudden death, pressure too great=dilation & abnormal rate)
• Renal: renal failure (vascular changes= arterial intimal fibroelastosis, hyaline arteriolosclerosis, chronic renal failure due to dec in function)
• Cerebrovascular: cerebrovascular accident (hypertensive encephalopathy, inc risk of berry aneurysm, subarachnoid haemorrhage, intracerebral haemorrhage)

Question 21

What is a hypertensive crisis?

Answer 21

• AKA malignant hypertension
• BP: >180/120
• Acute hypertensive encephalopathy, renal failure, retinal haemorrhages
• Urgent treatment to preserve organ function

Question 22

Describe pulmonary hypertension

Answer 22

• Pulmonary artery
• Caused by: loss of pulmonary vasculature, chronic obstructive lung disease, pulmonary fibrosis/emboli/thrombus, under ventilated alveoli
• Secondary to LVF
• Systemic to pulmonary artery shunting
• Causes inc RV work to pump blood, RV myocardial hypertrophy without dilation, systemic venous congestion as RVF develops

Question 23

What are risk factors for cardiovascular disease?

Answer 23

• Male
• Hypertension
• Smoking
• High blood cholesterol
• Low blood high density lipoproteins
• Diabetes
• Sedimentary lifestyle
• High alcohol use
• Obesity
• Ethnicity-south asian

Question 24

What is the Framingham risk score?

Answer 24

-Calculates individual’s risk of CVD based on multiple risk factors